What's a good method for eliminating carcinogens from your body?

I used to have a terrible nervous habit of gnawing on, and eating, flexible plastic and pieces of paper. Now I am concerned that the parts of these items that I have ingested have loaded me with carcinogens or other harmful chemicals. Obviously, I have dropped the habit, but what can I do now to reduce the risk of repercussions from what I've done in the past?